Supernatural Serum
by Dark-Supernatural-Angel
Summary: When Queen Consolidated is broken into by a man with suspicious strength, CEO Oliver Queen is surprised to find two federal agents on the case. Despite the new enemy in town, the Arrow is more confused by how these two agents seem to know Felicity Smoak. [Different spin on 2x08/2x09 with no Barry Allen] [Crossover with "Supernatural"]. Plz R&R!
1. DAY ONE - Unknown Investigators

"**Supernatural Serum"**

**Disclaimer: **I don't own the characters; those belong to their original creators. The way it's all stringed together is of my making. No profit is being made out of this (*sigh* unfortunately).

* * *

**Backstory:**

\- Felicity meets the Winchesters in 2012 (reality; 2011-2012 / verse; 2012-2013 aka S7) = S9 (verse; 2015-2016)  
\- Timeline of "Arrow" has been pushed forward by **2 years** (therefore Oliver is shipwrecked in 2009 and saved in 2014) = S2 (2015-2016)

**Ages:**  
\- Dean Winchester (b. 1979)  
\- Sam Winchester (b. 1983)  
\- Oliver Queen (b. 1987, not 1985) = 4 years younger than Sam  
\- Felicity Smoak (b. 1990, not 1988) = 3 years younger than Oliver and 11 years younger than Dean  
\- John Diggle (b. 1979, not 1977) = 8 years older than Oliver and the same age as Dean  
\- Roy Harper (b. 1993, not 1991) = 3 years younger than Felicity and 10 years younger than Sam

***Ages of the "_Arrow_" characters are the same here as they are on the show (it's just the changes in dates that are different)

* * *

**REASON why this is listed under "**_**Arrow**_**" only:** because of Felicity.

* * *

**TIME **= December 2015 (Winchesters have known Felicity for 3 years)

* * *

**Summary: **When Queen Consolidated is broken into by a man with suspicious strength, CEO Oliver Queen is surprised to find two federal agents on the case. Despite the new enemy in town, the Arrow is more confused by how these two agents seem to know Felicity Smoak. [Different spin on 2x08/2x09 with no Barry Allen] [Crossover with "Supernatural"]

* * *

**NOTE:** I'm only posting this today to honor Dean Winchester's fictitious birthday.

* * *

***SPN*Arrow*SPN*Arrow*SPN***

* * *

**Chapter 1:  
DAY ONE - Unknown Investigators  
**

There was a police perimeter set up along one of the warehouses that belonged to Queen Consolidated as they investigated the break in that happened the previous night. Among the investigators was Officer Quentin Lance who was one of the first policemen to arrive at the scene of the crime. And it was an odd crime as the robbery resulted in the metal door of the warehouse being ripped off its hinges. Officer Lance found it to be very peculiar.

Officer Lance and his men weren't the only ones at the scene. Oliver Queen, current co-CEO of Queen Consolidated, was also present to check the latest damage to his family's company. He was accompanied by his executive assistant and his bodyguard, Felicity Smoak and John Diggle, who just so happen to be his most trusted confidants.

Oliver and Diggle were crouched down as they looked over the crushed metal door.

"This door was made of expanded reinforced titanium," Diggle commented before he stood to face Lance, "What did they use to do this?"

Officer Lance shrugged, "Not sure yet. No sign of any explosives." He started to walk around the door with a nervous Felicity falling into step just behind him, "Maybe a crane or a forklift was used. But I'm guessing there were at least three of them, maybe four." His eyes landed on the turned over barrels that were taped off. "And given how quick they got in and out of here, they were fast."

Felicity turned to look at Oliver and Diggle as they joined her. She gave them a questioning look but the men only shook their heads. They were as stumped as she was on the situation.

Unaware of the little exchange, Officer Lance continued to walk further into the warehouse. The trio quickly followed after him.

"Any idea what these guys were so hot to break in here for?" He asked as he tried to spot any disturbances in the warehouses' configuration. It wasn't like the entrance way where there was an obvious sign of a struggle.

The rest of the warehouse was still as organized as ever.

"You didn't happen to leave a spare earthquake machine lying around, did you?" Officer Lance wondered out loud but when he turned around, he was faced with an unimpressed Oliver. Lance cleared his throat, "Sorry."

"This is what we're able to pull off the security cameras." A technician interrupted as he walked up to them.

The quartet turned around and waited for the technician to play the security footage from his tablet.

The footage showed a masked man throw the two guards around as if they weighted nothing until he finally threw a metal container at the security camera, cutting off the feed immediately.

"He was the only guy we got on video," The technician explained once the video ended, "The rest of the crew must have come in after him."

"That is not always the case," a deep voice interrupted from across the warehouse, causing everyone to turn towards the newcomer. With everyone focused on the newcomer, no one noticed the surprise that flickered over the petite woman's face before she masked it behind her glasses.

The newcomer appeared to be a tall thirty-something male with short dirty-blonde hair. He was in a suit and he wasn't alone. A few feet behind him was another male in a suit, a taller one who had shaggy brown hair. His attention had been caught on one of the stations in the warehouse before he quickly moved to rejoin the first man.

"Sorry for the delay." The man continued once he got closer to the original group. "We wanted the coroner's report before we checked out the crime scene." He stopped a few feet away from the others with his partner joining him a few moments later. While the first man didn't have anything else with him, the second one appeared to have a tablet of his own in his hands.

"Great," Lance drawled out, "Who the hell are you?"

The two men reached into the jackets, "I'm Agent Anderson," the first man introduced before he motioned towards the second man, "this is my partner Agent Bolan."

By this time, both of their FBI badges were out and shown towards the group before they put them away again.

"We were just finishing up a case in Central City when we got the call to come down here from our supervisor," Agent Anderson explained with a shrug, "Apparently the unexplained elements of the case caught our boss' attention."

Lance gave the agents a skeptical look, "So you actually think that one guy ripped through this door like it was tin foil?"

"We never truly rule anything out sir. The coroner's report suggests the possibility of one guy doing the damage," Agent Bolan commented as he flipped open his tablet. He tapped a few things into the screen before he turned it towards the group, who all stepped forward to have a closer look.

Everyone could now see a medical photo from the autopsy for one of the guards.

"Do you see the marks on the guard's neck?" Agent Bolan pointed along the peculiar bruise patterns, "The bruising pattern fits only one hand and it takes about 1,250 foot-pounds of torque to break someone's neck."

Oliver paled a bit at the implication, which didn't go unnoticed by Bolan's partner.

"By the looks of it, I'm guessing you don't know how hard it is to break someone's neck." Agent Anderson commented as he stared at Oliver.

Oliver blinked, "Hmm?"

Agent Anderson quirked an eyebrow at him as if goading him to answer which Oliver thought was weird.

Oliver just shook his head at the question, "No. No idea."

"Uh," the technician cleared his throat, causing Oliver and the others to give him their attention. "We're going to need a list of the entire inventory here to figure out exactly what was stolen."

"That would be helpful but I think I already know what was stolen," Agent Bolan interrupted which brought everyone's attention back to him. His partner even gave him a questioning look. "A centrifuge," it was all Bolan said before he turned around and headed back the way he originally came from.

Knowing his partner's antics, Agent Anderson turned and followed after him. What surprised everyone that was left behind was that Felicity didn't hesitate to follow the two suited men. This caused Oliver and the others to follow her.

Once everyone was closing in, Agent Bolan continued his explanation, "My guess is an industrial centrifuge based on the three column base set up that was left behind." He pointed towards the three column base at his feet. The base had misshaped bolts protruding from the concrete. Everyone spread out around the broken base as they looked at the damage.

Before anyone could ask about how Bolan knew about the centrifuge being the missing device, he pointed to a table near the base that they had passed by. "The equipment left behind also suggests that a centrifuge was set up here."

Anderson crouched down to take a closer look at the damage, "Judging by this, the device was just ripped out of the ground like it weighted nothing. They didn't even bother to detach the thing first before taking it."

Curious by the deduction, the technician moved his hands over the computer's mouse which caused the screen to come alive. On the screen was a company log-in for the missing centrifuge. The stunned technician turned around to see the crouching Anderson smirking up at his partner. The technician still wanted to do an inventory check just in case.

Lance frowned, not really seeing the significance of the discovery, "And what exactly is a centrifuge?"

Before Bolan could answer, Felicity beat him to it, "It separates liquids." Everyone's head turned towards her yet her attention was focused on Lance. "The centripetal acceleration causes denser substances to separate out along the radial direction." When she was done,she looked back down at the broken bolts.

With everyone's attention on Felicity, no one noticed the smirk on Anderson's face as he looked at her.

"And the lighter objects move to the top," Bolan added in, bringing all attention back to him.

Felicity smiled, "Precisely." She looked up at the agent, "What did you say your name was again?"

The taller man returned the smile, "Agent Sam Bolan."

"Felicity Smoak."

Oliver blinked at the introduction and looked to his friend, only to see an unfamiliar glint in her eye as she smiled at the agent. He turned to look at the agent only to find the same glint in his eyes. Oliver didn't like it.

As he moved around his partner to stand on the empty side of the broken base, Anderson cleared his throat.

Felicity saw Sam discreetly roll his eyes before she turned to give her attention to his partner.

"It's a pleasure to meet you Miss. Smoak." Anderson spoke once he felt her eyes on him.

Felicity chuckled under her breath, "You too Agent…"

"Dean Anderson," the agent finished for her with a smirk on his face.

Finding the exchange odd, Lance looked towards Oliver only to find that he too had a confused look on his face.

Noticing this, Sam coughed in hopes of bringing his partner's focus back.

Which it did.

Dean cleared his throat and stepped back. "Despite the weight of the device, the cracks in the floor suggest only one guy." He explained as he pointed to the footprint trail that he was standing beside. "Only one set of tracks."

Sam and Dean looked to one another as Oliver crouched down to take a closer look at the base.

"There has to be another explanation," Lance was still skeptical about the one-thief theory.

"If you think like that then you'd never get this solved _sir_," Dean quipped with a smirk, "Sometimes you have to think outside the box."

Lance stared at Dean, like Oliver had done to him earlier, before he pulled Felicity off to the side.

"You might want to fill our mutual friend in on this," Lance whispered to the Arrow's IT girl.

"Don't worry," Felicity gave the older man a tight lipped smile, "I'm sure he's already on it."

Lance nodded, unaware that the vigilante he wanted was already there with him.

When Lance and Felicity moved back towards the broken base, they noticed that they were a man short.

"Where's your partner?" Lance questioned as he looked at the taller agent, who was examining the area around the base a little more thoroughly with Diggle.

Sam looked up, "He went to check where the trail ended."

Lance nodded but it was Felicity that noticed that Sam didn't have his tablet anymore. She gave the agent a questioning look only for him to give her a shrug back as his answer.

Felicity sighed before she moved towards Oliver, "I think we should head back."

Oliver looked up at her.

"You have a few meetings back at the office that you need to attend." Felicity clarified as he straightened himself up, "I couldn't reschedule those."

Oliver nodded, "Its fine Felicity. I don't think we can do much here." He walked up to Lance and requested to be updated on the case's progress before he headed towards the exit with Diggle on his tail.

Felicity sighed as she turned to Sam, "If you need any further help, I'll be happy to assist you Agent Bolan."

Sam chuckled, "We'll keep that in mind Miss. Smoak." He waved towards the exit, "You better get going."

Felicity nodded before her heeled feet scurried her towards the exit. She waved goodbye to Lance as she passed him before she was out of sight.

Lance chuckled to himself. "She's definitely something."

"I'm beginning to see that," Sam agreed yet Lance noticed this hidden glint in the agent's eyes. It was like he knew something that Lance didn't.

Before Lance could question it, they were interrupted by Agent Anderson.

When he got to his partner's side, he did a double take around the area. "Where did the others go?" He was trying to find the petite woman and yet he was coming up empty.

"Mr. Queen was needed back at the office," Sam told his partner before he looked down at the tablet he had given Dean before he left to follow the trail. "Find anything?"

Dean shook his head, "Nope." His grip tightened on the tablet, "I think we're done here."

Sam nodded before he reached into his pocket. He pulled out a card and handed it to Officer Lance, "In case anything new comes up, we can be reached here."

Lance took the card and glanced over Agent Bolan's contact information. "I'll keep that in mind."

The agents said their goodbyes before they headed out towards their 1967 black Chevy Impala. They didn't say anything until they were in the comfort of their car.

Sam turned in his seat and looked at his partner, "Okay, what did you really find?"

Dean rolled his eyes as he flipped open the tablet and tapped a few things onto the screen before he turned it around. "The camera above the door caught the thief in the parking lot. The exit wasn't left in great condition either. It was like a bull had rammed into it or something," he explained as he played the video. When he found the footage, he had it transferred to Sam's tablet before anyone else checked the outside feeds for the thief's escape.

Sam watched the security footage of the thief carrying the centrifuge on its shoulders for a short distance before loading it into a large truck.

"That was definitely not normal." Sam commented as he motioned for the tablet. He wanted to go through it again.

Dean sighed, "That's not all. I didn't find any traces of sulfur when I was following the cracked trail." He ran a hand through his hair, "Sammy, this is looking like nothing we thought it was."

Sam tapped the screen a few times, "Well the EMF meter didn't go off when I was around the base so there is another bust." He sadly added before he tapped the screen again.

"This doesn't make sense. Who the hell would want a centrifuge anyways?" Dean questioned with a groan.

Sam shrugged, "I have no idea but is that a plate?" He asked as he showed Dean the paused image of the thief closing up the truck's door. It was blurry but Dean could make out the outline for a license plate.

"I can't make it out," he looked between Sam and the image, "Do you think you can clean it up?"

Sam frowned, "I can try but she might have to do it."

Dean quirked at eyebrow, "Are we really going to cross that line?"

Sam shrugged, "Well, her boss' company is the one that was hit. It would make sense why we would see her without raising suspicions," he looked back at Dean, "you know for follow-ups with the investigation."

"Alright little brother, set it up," Dean instructed as he turned the Impala on and drove out of the parking lot.

* * *

***SPN*Arrow*SPN*Arrow*SPN***

* * *

**Dialogue Disclaimer: **Any recognizable _Arrow_ dialogue came from 2x08 "The Scientist".

_**Supernatural**_** Aliases:** FBI Agent Anderson was used in 7x02 while FBI Agent Bolan was used in 8x13…both aliases were used by Dean.

* * *

**A/N #1: **And there you have it! The first chapter of what I hope to be my first multi-chapter SPN/Arrow story! Dean Anderson and Sam Bolan are on the case! So what did you guys think? What do you think will happen next? What parts of Arrow canon will remain and which ones won't? I'd love to hear your guesses!

**A/N #2:** If you love the crossover idea, then check out my collection **"Mysterious Smoak"** for more oneshots set in the Supernatural/Arrow crossover universe!

* * *

**Originally Posted: **January 24, 2015


	2. DAY ONE – Afternoon Visit to QC

"**Supernatural Serum"**

**Disclaimer: **I don't own the characters; those belong to their original creators. The way it's all stringed together is of my making. No profit is being made out of this (*sigh* unfortunately).

Manipulations of the cover art/image are mine though.

* * *

**Backstory:**

\- Felicity meets the Winchesters in 2012 (reality; 2011-2012 / verse; 2012-2013 aka S7) = S9 (verse; 2015-2016)  
\- Timeline of "Arrow" has been pushed forward by **2 years** (therefore Oliver is shipwrecked in 2009 and saved in 2014) = S2 (2015-2016)

* * *

**TIME **= December 2015 (Winchesters have known Felicity for 3 years)

* * *

**Ages:**  
\- Dean Winchester (b. 1979 / 36)  
\- Sam Winchester (b. 1983 / 32)  
\- Oliver Queen (b. 1987 / 28)  
\- Felicity Smoak (b. 1990 / 25)  
\- John Diggle (b. 1979 / 36)  
\- Roy Harper (b. 1993 / 22)

***Ages of the "_Arrow_" characters are the same here as they are on the show (it's just the changes in dates that are different)

* * *

**REASON why this is listed under "**_**Arrow**_**" only:** because of Felicity.

* * *

**Summary: **When Queen Consolidated is broken into by a man with suspicious strength, CEO Oliver Queen is surprised to find two federal agents on the case. Despite the new enemy in town, the Arrow is more confused by how these two agents seem to know Felicity Smoak. [Different spin on 2x08/2x09 with no Barry Allen] [Crossover with "Supernatural"]

* * *

**NOTE:** Happy Friday the 13th / Happy Early Valentine's Day (Unattached Drifter Christmas)

* * *

***SPN*Arrow*SPN*Arrow*SPN***

* * *

**Chapter 2:  
DAY ONE – Afternoon Visit to QC**

At Queen Consolidated, Felicity was hard at work. It's been a few hours since she returned to the office with Oliver and Diggle and once they had returned, she only had a few moments to go over any last minute meeting details with Oliver before he was swept up in the business bustle.

While Oliver was busy in the first meeting, Felicity prepared his notes for his second meeting before she was able to get back to her regular executive assistant duties. They were pretty mundane and routine for her taste but she did like the simplicity of it because it allowed her to focus her time on more challenging issues. Originally when she finished her meeting preps, the former IT employee had planned to dig a little deeper into the robbery back at the warehouse. The circumstances of the whole thing really creeped her out…and then to see two FBI agents coming onto the scene, it freaked her out even more.

With everything on the company computer completed, Felicity was ready to execute her plan when an email alert from her tablet caused her fingers to freeze over the keyboard. She gave her bag a curious look before she reached down and grabbed the locked tablet. Once unlocked, Felicity was surprised to find that she had a video attachment with a short email message attached to it.

_**Sorry for crossing the line.  
We found a possible plate from the parking lot footage.  
We'll drop by in a little while.**_

_**S &amp; D **_

Felicity sighed as she reread the email. She couldn't be mad at them. She just wished that they had given her more of a head's up before they showed up in her theoretical backyard.

Refusing to think about the complexity any further, Felicity opened the video and watched the thief with wide eyes as he escaped in his getaway car. She could immediately see why they had sent her the video. She tapped a few commands into her tablet before the video was sent into her enhancement program. While that was happening, the video gave her an idea as to where else she could look for possible footage…maybe there was another vantage point of the thief's escape.

When Oliver came back from his first meeting, Felicity had to put her searches on hold to prep him for his next meeting. She never even gave him a chance to ask about any updates for the robbery. She only talked about his second meeting so he complied with her tactics.

Once Felicity returned to her desk, she got back to work on her video search. Even though her focus was on her tablet, she was still able to perform the duties required of her as Oliver's EA when they were required. It was a little different than usual due to one of their warehouses being robbed but she was able to keep all questions to a minimum.

With her attention shifting between her two jobs, she hadn't noticed when Oliver returned to his office.

.*.*.*.*.*.

When Oliver returned to his office after his second meeting, he wasn't surprised to find Felicity huddled over her desk with her eyes glued to the screen while her fingers tapped incessantly over the keyboard. It was a familiar sight for him to see, whether it was at her desk or down in the Foundry, he always found her like that at some point. He was tempted to interrupt her and ask about any updates about the robbery but in the end, he decided against it. He made his way towards his office without disturbing her. Instead of heading to his desk, he detoured to the window that overlooked the city. Oliver thought the current downpour fit his mood perfectly.

He tried to get some work done for the company and yet he found that his mind was elsewhere. So much had happened since he woke up that morning, it still boggled him. There were many times throughout his meetings where his mind had wandered over to that very fact. Just that morning he was welcoming his mother back into the company after she was acquitted only to be told moments later that one of his company's warehouses was robbed the previous night. And the way the robbery occurred, that was another issue entirely. The similarities brought up memories that Oliver wished stayed buried in his past and he feared that they will be unburied sooner than he'd like.

The CEO was brought out of his memories when Diggle called out his name as he walked into the office. Oliver turned from his spot by the window, giving his friend his full attention.

"I got the final inventory from applied sciences," Diggle handed the inventory list to Oliver, who started to look over it, "Agent Bolan was right. The only thing missing is a centrifuge."

Before Oliver could ask anything else, the clicking of Felicity's heels heading their way caught their attentions.

"You have to see this," Felicity greeted as she walked in with her tablet in hand, "I pulled up CC-traffic camera footage from across the street of applied sciences," she stopped in front of them, tapped a few things onto her tablet before she turned it around to show the men, "This is three minutes after the alarm went off."

Oliver and Diggle watched a side view of the thief lifting the centrifuge off his shoulders and into a white truck. Diggle gave Oliver a side glance, hoping to gauge his response to the video, while Oliver's eyes remained glued to the tablet.

Unknown to them, Felicity had shown them the second video she had viewed.

When watching the first video she had received, it got her thinking about possibly getting a closer look to the truck. Originally she had feared that the thief may have destroyed any cameras he spotted like when he first arrived but luckily for Felicity, the thief was too preoccupied with the centrifuge to take notice of the security cameras that he had passed. So while the first video captured a distant view of the thief and his truck, it did provide a possible plate she could work with while the second video captured a closer view of the thief, providing a better look at his appearance, and yet the plate wasn't visible at all. She knew that she should have shown both videos to Oliver and Diggle and yet Felicity decided to hold off on that move.

Before Oliver could ask if that was all that Felicity found, movement out of the corner of his eyes caught his attention. They weren't alone anymore and Diggle noticed that as well.

"Can we help you with something, Agents?" Oliver asked, causing Felicity to turn around and see their new visitors.

Agents Anderson and Bolan walked towards the open office entryway.

"We just have some follow-up questions and evaluations for the investigation, Mr. Queen," Agent Bolan explained with a friendly smile on his face.

Oliver nodded; he kind of expected a follow-up but he thought Officer Lance or someone else from the SCPD would be dropping by, not these foreign agents.

"We won't be a bother," Agent Anderson added as he took a step into the office, "Miss. Smoak actually volunteered her assistance to us so that we don't interrupt your busy schedule." He finished and yet when he noticed that a frown started to form on Oliver's face, the agent couldn't help but smirk.

Luckily for Felicity, neither Oliver nor Diggle saw her roll her eyes at the agent. She was surprised, however, when she felt her elbow being tugged backwards, forcing her to step back a bit and into Oliver's personal space. She turned and gave him a questioning look.

"What are you doing?" Oliver whispered yet she could tell that he was trying to reel himself in and not react to the new intrusions in his life.

"We need to find this intruder. And they seem to know more about it than any of us," she sighed before she looked over her shoulders to glance at the agents. She saw that they were taking in their new surroundings, as if doing so was a way to give them the privacy they needed to talk, "I'd say we need them," she turned and looked up at Oliver, "Wouldn't you?"

Oliver gave a reluctant hum. He hated to admit it but she was right. They needed this intruder to be caught but Oliver feared just how much these agents knew about the situation. What happened if they got too close to the case? Oliver couldn't afford anymore collateral damage on his conscience.

Felicity smiled at the billionaire before she turned and walked towards the agents. "I'll show you around." She walked between them before she led the way outside the office, "Before we get started, would you agents like some coffee? I know this great place just around the corner."

Oliver and Diggle watched as the agents followed Felicity to her desk and waited for her to grab her coat and bag before they followed her out to the elevators. Diggle had to reign in his amusement when he overheard Felicity's coffee offer since she still refused to retrieve coffee for Oliver.

When they couldn't hear her heels anymore, Oliver turned back to look out the window while Diggle turned towards his friend, "Why am I getting the feeling that you know more about this than Felicity's new friends?" Since the warehouse, Diggle had been getting the impression that Oliver was holding something back from them, more so than usual.

Oliver sighed, "Pray that I'm wrong."

The sun continued to glint onto Oliver's face but that didn't stop the thunder to clash in the sun-shower the city was having.

.*.*.*.*.*.

There was silence between Felicity and the agents but that ended once they were alone in the elevator.

"I didn't know you were coming," Felicity spoke while looking forward with her back straight, keeping her professional persona for the cameras inside the elevator. Because of the reflective doors, she could still see the men standing behind her.

Over Felicity's head, Sam and Dean Winchester looked to one another.

"After what happened a few days ago, why wouldn't we be here?" Dean questioned as he looked at her through the reflective surface. After they heard what happened to her, the brothers had agreed that their next stop was going to be Starling City so that they could check up on her for themselves.

Felicity tensed, "I said I was fine." She didn't like to think about it. So much went wrong and it was all because she made the wrong move. No matter how much reassurance that Oliver gave her about it, Felicity knew deep down that she made the wrong move. And that wrong move ended a man's life.

Sam's look at her reflection softened, "You were attacked in this very building Felicity. It's okay if you're not fine.**" **When they got news that Felicity had been taken hostage by Count Vertigo in the very building she worked in, the Winchesters were shocked and furious. They were furious that they couldn't be there for her as well as the fact that they had to learn the news from Kevin Tran (who was actively yet discreetly keeping tabs of what was going on in Starling City for the brothers while doing his own tablet research back at the bunker) instead of from Felicity herself. When they finally got a hold of her, Felicity repeatedly told the brothers that she was fine but Sam and Dean knew that she was shaken and not completely okay; physically maybe but emotionally, not so much. She was supposed to be away from danger and yet it seems to find her no matter where she went.

"One attack isn't going to hold me back," Felicity defended with a sigh, "You still should have told me." It wasn't that she wasn't glad to see them. She just never thought that she would see them while she was at work. She knew they were heading towards the West Coast after they learned about the Count but she never thought she'd run into them like this. They were coming from Hurleyville, New York so she thought she'd have a week or two before they showed up.

Sam bowed his head, "We were just as surprised as you were to see us when we heard the report over the wire." He explained as he thought back to when they heard the police report over Dean's police scanner. They were just outside the city when they first caught wind of it. They would have just ignored it but when they heard about the metal door being ripped apart like it was nothing, they just had to check to see if it was their kind of thing.

"Look on the bright side; at least we're in town for the holidays." Dean quipped in hopes of lightening the mood.

Felicity nibbled on her lower lip, "I'm not ready for them to find out."

Sam and Dean looked to one another again.

"Then they won't," Dean reassured her before he cleared his throat, "Now did you get the footage?"

Felicity nodded but before she could say anything more about it, the elevator opened up to the lobby. She led them out of the building and to the park across the street. She had spotted the black Chevy Impala along the way before she took a seat on a free bench in one of the park's gazebos; it was the perfect cover during a sun-shower. The agents followed her lead and sat on either side of her.

Unperturbed by the seating, Felicity whipped out her tablet and brought up the same video that she had shown Oliver and Diggle.

"I found this before you got here but I did manage to get a plate from the video you sent me." Felicity explained as Sam and Dean watched the video. When it was finished, she brought up the results from the first video. In black and white, Sam and Dean could see the enhanced license plate. Their hope for a lead was dashed with Felicity's next words; "It came back stolen."

Dean groaned, "Figures."

"Who filed the report?" Sam questioned as he took in the details on the tablet's screen.

Felicity tapped the screen a few times, bringing up the police report for the brothers. She held the tablet out so that both brothers could see its contents, "The vehicle belonged to a sugar refinery located two miles from the warehouse. They filed the report a few days ago."

"What are the chances that the thief is using the refinery as his home base?" Sam asked as he tilted the tablet towards him.

Felicity frowned at the thought. "The refinery is still in business. Wouldn't that draw attention to him instead of away from him?"

Dean ran his hand through his hair as he gave his brother's question some thought, "It would make sense though."

Felicity turned towards Dean with a questioning look, leaving the tablet in Sam's hands.

"It would be less suspicious for a company truck to come and go as it pleased as opposed to an unmarked vehicle or one from another company," Dean explained as he looked back at her.

"Have you been able to track it?" Sam asked Felicity as he handed the tablet to Dean to have a look.

Felicity sighed, "I've set up the search for it. Nothing has come up yet. What did you guys come up with?" She looked between the two of them with a hopeful expression. With the weirdness of this case, the only reason she wasn't panicking was because Sam and Dean were there and if they were there, then it meant that they could provide some type of explanation for all the weirdness wrapped around the centrifuge robbery.

Sam nervously scratched the back of his neck, "We're still working on it. Some things aren't adding up here."

Dean hummed in agreement as he passed the tablet back to its owner. Once the device was safely tucked away into her bag, Dean scooted towards Felicity.

"Do you think you can get us into the warehouse again? I don't feel like scaling any fences tonight." He whispered in her ear with a slight teasing tone.

Felicity chuckled, "Are you getting too old for that Dean?"

Dean narrowed his eyes yet there was no real fire behind them, only amusement, "Never."

Sam rolled his eyes as the two ignored him. It wasn't anything new for him but he did like that his brother was enjoying himself again. It was hard not to lighten up when around Felicity.

"If we're going back then we better get going," Sam interrupted before they diverted away from the plan.

Felicity stood up and brushed down her coat before she looked back at the brothers, "Follow me then."

She turned on her heels and walked back towards Queen Consolidated before the brothers got a chance to stand up.

* * *

***SPN*Arrow*SPN*Arrow*SPN***

* * *

**Dialogue Disclaimer: **Any recognizable _Arrow_ dialogue came from 2x08 "The Scientist".

_**Supernatural**_** Places:** Hurleyville, New York is the main location for 9x07 ("Bad Boys"). Therefore this takes place after 9x07.

* * *

**A/N #1: **And there you have it! Felicity is keeping things from Oliver and the Winchesters have a lead to work on. So what did you guys think? What do you think will happen next? What parts of Arrow canon will remain and which ones won't? I'd love to hear your guesses!

**A/N #2:** You guys are truly amazing readers! I truly didn't expect the response that I got for this story. After the first week, I already had 22 reviews, 1,000 hits, 59 favorites and 122 followers! That just blew my mind away and it's all thanks to you guys! It truly means the world to me to have your support! **THANK YOU!**

* * *

**Self-Promotion:** If you love the crossover idea, then check out my collection **"Mysterious Smoak"** for more oneshots set in the Supernatural/Arrow crossover universe!

* * *

**Originally Posted: **February 13, 2015


	3. DAY ONE – Latest Developments

"**Supernatural Serum"**

**Disclaimer: **I don't own the characters; those belong to their original creators. The way it's all stringed together is of my making. No profit is being made out of this (*sigh* unfortunately).

Manipulations of the cover art/image are mine though.

* * *

**Backstory:**

\- Felicity meets the Winchesters in 2012 (reality; 2011-2012 / verse; 2012-2013 aka S7) = S9 (verse; 2015-2016)  
\- Timeline of "Arrow" has been pushed forward by **2 years** (therefore Oliver is shipwrecked in 2009 and saved in 2014) = S2 (2015-2016)

* * *

**TIME **= December 2015 (Winchesters have known Felicity for 3 years) / Post SPN 9x07

* * *

**Ages:**  
\- Dean Winchester (b. 1979 / 36)  
\- Sam Winchester (b. 1983 / 32)  
\- Oliver Queen (b. 1987 / 28)  
\- Felicity Smoak (b. 1990 / 25)  
\- John Diggle (b. 1979 / 36)  
\- Roy Harper (b. 1993 / 22)

***Ages of the "_Arrow_" characters are the same here as they are on the show (it's just the changes in dates that are different)

* * *

**REASON why this is listed under "**_**Arrow**_**" only:** because of Felicity.

* * *

**Summary: **When Queen Consolidated is broken into by a man with suspicious strength, CEO Oliver Queen is surprised to find two federal agents on the case. Despite the new enemy in town, the Arrow is more confused by how these two agents seem to know Felicity Smoak. [Different spin on 2x08/2x09 with no Barry Allen] [Crossover with "Supernatural"]

* * *

**NOTE:** I'm posting this today in honor of **Jensen Ackles' birthday**, the amazing actor who plays Dean Winchester.

* * *

***SPN*Arrow*SPN*Arrow*SPN***

* * *

**Chapter 3:  
DAY ONE – Latest Developments**

After some time roaming around the warehouse, Felicity and the Winchesters met back up at the damaged centrifuge base.

"Find anything new?" Felicity asked once Dean returned to her side.

When Dean went to roam the warehouse, Felicity and Sam headed for the security hub. Together they combed through the security feeds but when they came up with nothing, they returned to the rendezvous point. As they waited for Dean, Felicity wanted to see if she could get any information about the stolen centrifuge from the assigned computer terminal Sam had noticed earlier. She was able to use her company ID to log in but there wasn't much useful information on the computer.

Dean shook his head, "There were no EMF signals anywhere so ghost possession is out of the question and there was still no sulfur which cancels our original thought that demons were involved." His part of the recon was to retrace the thief's steps and try to figure out any other paths that first went unnoticed. Throughout his trek, Dean didn't smell any sulfur and he had no readings on his EMF meter. "What about you guys?"

It was Felicity's turn to shake her head yet her attention was still on the computer terminal. She was still trying to sift through the data in hopes of finding something of use to them.

Noticing that Felicity's attention was elsewhere, Sam filled his brother in. "There was no interference in the security feeds so there was no tampering on this end. There was nothing new for us to find here."

Dean groaned at the news, "This just doesn't make sense. It was supposed to be demons."

Felicity stopped and looked over her shoulder, "I thought demons were never supposed to make sense."

Dean waved a dismissive hand at her. He remembered telling her that when they first got to know one another a few years back.

Felicity huffed.

Sam sighed, "Usually but this time their motivations for this don't add up." He walked to stand on the other side of the computer terminal. "Like why would demons go through all this trouble to steal a centrifuge if they could have easily possessed the guards and perform an inside job without sounding the alarms? The guards had no anti-possession markings on them so there wasn't anything stopping a possession from happening." He pointed out as he remembered the coroner's report; the guard had no marks on him aside from the bruising that led to his death.

Felicity nodded along. Sam did have a point. Demons had all sorts of powers that could bring a spotlight onto them or keep them under the radar. If demons wanted to steal something and not bring attention to themselves or to the act itself, they would have just possessed those closest to the thing they wanted to steal. They wouldn't want to risk hunters catching onto their plans but this? This robbery was just asking for attention.

Felicity looked between the brothers, "Could it be something else?"

Sam shrugged, "It's possible…" a whole list of creatures starting reeling through the hunter's mind again but there were still too many variables to consider, "but we're stumped on the idea of why a supernatural entity would want a _centrifuge_ in the first place."

"But why in the world would _anyone_ steal a centrifuge that was guarded by a fortune-500 company?" Dean interrupted as he moved to stand beside Felicity; the very thought bothered Dean, "Supernatural or not, why would anyone want to do that?" He questioned with a raised eyebrow directed at her.

Felicity typed a few things into the terminal before an information page popped up. "The inventory list stated that the missing centrifuge was the Kord Enterprises 2BX-900." She pointed to the screen where the product's code was listed.

Dean scowled, "Like that is supposed to mean something to me. English please Fee."

_He did have a point_, Felicity thought as she skimmed over the information again. Aside from the centrifuge's model, there wasn't anything different about it. It did the same thing that other centrifuges did except that it did it on a bigger scale. Felicity was ready to tell Dean that but Sam beat her to it.

"Centrifuges are meant to separate liquid components from one another," Dean tilted his head towards his brother as he listened; "The industrial size suggests that a lot of liquid separation needs to be done." Sam explained as best as he could for his brother. It wasn't that Dean wasn't smart (his older brother was a damn genius if anyone asked Sam), Dean just didn't bother with learning the technical jargon that had nothing to do with hunting.

Dean blinked as he thought over the explanation, "And that means nothing to me but it definitely doesn't sound good at all."

"Okay, so the question is what would the thief need to separate on a massive scale?" Felicity asked as she typed a few more things into the terminal before another screen popped up. This caused Dean to look over her shoulder to check out the screen while Sam moved around the table to see what had everyone's attention. It turned out that Felicity had found the ingredients that this particular centrifuge was able to process without a problem. She thought that finding the list might help them in some way.

"Is it just me or does this sound less like our kind of case?" Dean questioned as he read through the list; it all seemed like generic materials to him, nothing stood out.

"It wouldn't be if you factored out the super-human strength that appeared on many occasions throughout the robbery." Sam reminded his brother as he skimmed the list. He was able to recognize a few chemicals and drug compounds on the list.

Felicity turned around in her spot so that she could lean her back against the computer terminal. Her hands gripped the terminal's edge as she looked between the brothers. Even with her heels, Felicity still had to look up at them, "But can we really rule out the supernatural? I think the super-strength is a huge deal."

Dean shifted his stance with his side now touching the terminal as his arms crossed over his chest, "Well demons were the top choice of our list but like we said, there were no sulfur residues and there have been no demonic omens in the area."

As Dean spoke, Sam took out their tablet from the inside pocket of his jacket. He quickly turned it on and tapped the screen a few times before he showed the device to Felicity.

She recognized the database immediately as the one that she and Charlie Bradbury (a fellow hacker that the brothers had met a few months after they met Felicity) had created a while back. It listed creatures and their M.O.s in an organized manner. After meeting and hitting it off with one another, Felicity and Charlie both decided that they wanted to do something for the brothers to help them out since they ultimately saved their lives. Once the idea of a database came up between them, there was no stopping the women from following through with it. It took a while for them to complete the program but they had a lot of research to comb through first. They wanted to make sure that they had accurate intel worked into their program. It was only on a trial basis for the duo when Charlie first showed it to the brothers during her first trip to their Bunker headquarters. Felicity hasn't been to the Bunker yet but she has seen it through her web-chats with the brothers.

"A lot of other entities run on their instincts in order to survive but there are very few creatures that have the brains to rob anyone." Sam pointed out as Felicity watched the program list all the possible creatures that could have committed the robbery.

"Shapeshifters could do it," Dean added with a groan when he saw the creature pop up on the tablet's list; again, he was reading the list over her shoulder, "but then again they could have easily taken the spot of a guard and not make it look like a robbery." Dean really hoped that it wasn't a shapeshifter they were dealing with; he hated them with a passion. He didn't just hate them because they had the ability to shift into anyone they wanted. He hated them because ten years ago, one shapeshifter had taken his face and committed a bunch of crimes with it. Because of that shapeshifter, Dean had a murder charge haunting him for quite some time. It made avoiding the authorities all the more crucial for Dean.

Sam shook his head, "The thief was wearing a mask so we couldn't tell if there were camera flare ups or not on his eyes." He pointed out as he thought about their lack of suspicious footage in the security hub. The mask made it impossible to see any distinguishing features on the thief's face.

Felicity looked up at Sam with wide eyes, "I forgot about that." She hadn't been searching for that when she was looking through the security footage; she was more focused on finding his trail than anything else. She had completely forgotten to look for any supernatural elements that a camera could have picked up on.

_I've been spending too much time doing Arrow research, _Felicity silently reprimanded herself before she shook her focus back into place.

She tapped the tablet a few times, allowing the program to continue with its generated list, "What about a vampire? Or a werewolf?"

"You gotta be more specific with werewolves." Dean mumbled as he tapped the werewolf icon on the screen. This caused a branched out portion to occur that had more sub-types of werewolves.

Felicity's eyes widened at the new feature; she hadn't created that portion, "Oh." She looked up at Dean, "Since when has there been more than one type?"

Dean shrugged, "It's a long story."

"That can wait for later." Sam interrupted them, bringing their focus onto him, "Now our guy could be either a vampire or a werewolf, since both creatures have the strength and the robbery did happen at night. So it's a definite possibility."

Felicity looked up at Sam and sighed, "I'm sensing a 'but' to that statement."

The brothers laughed for a little but instead of Sam answering her, it was Dean.

"_But_ what the hell would be the motivation for either creature to steal a damn centrifuge?" All traces of laughter left his face as he mulled over his question. "Vampires want blood while werewolves want human hearts." He clarified with the creatures' most basic needs. There was no need to understand creatures that functioned off their baser instincts. However, it always irked Dean when creatures acted outside their norm; it just complicated things for him and his brother…and now for Felicity too.

"Maybe it's not a supernatural motive but a personal one," Felicity suggested before pursing her lips together in thought. She didn't like the possibility but it was one that they couldn't overlook.

Sam sighed as he rubbed the back of his neck, "That would complicate things."

"So what now?" Instead of taking the lead in regards to research, Felicity left the decision up to the brothers. Because the case had supernatural elements to it, she gave them the lead since they were the experts.

"We keep looking." From his spot by her side, Dean surveyed the empty warehouse floor once again, as if scanning the place would somehow unearth a clue they had missed before, "They always slip up somewhere. We just have to find it."

* * *

Meanwhile in an alleyway just behind Verdant, Sin anxiously awaited alone until she was joined by Roy and Thea. She was surprised to see the latter when she only called the former to meet up with her.

"Sin, you said this was an emergency." Roy said, his version of a greeting, as he approached his friend. He and Thea were meant to have lunch with Moira Queen when he had gotten Sin's text.

Disregarding Roy for a moment, Sin turned to his girlfriend, "No offense, but Thea, you shouldn't be here." It wasn't that Sin didn't like Thea, it was that with Thea there, Sin couldn't openly talk to Roy about her emergency like she had wanted to in the first place.

Thea gave Sin a bemused look, "In the alleyway of the club _I _own?"

Sin raised an eyebrow at the heiress for the claim since everyone knew that the club really belonged to Oliver Queen.

With the look directed at her, Thea crossed her arms over her chest and gave a defying look of her own, challenging the other girl to say something about the club's ownership to her.

Not seeing any budging from Thea after that, Sin sighed. "It's my friend Max. He's missing. I haven't seen him for a week. No one has. Something happened to him." She explained before she looked directly at Roy, "I figured you knew _someone_ who could help." She emphasized in hopes that he understood that she was referring to the Arrow.

Roy started to panic on the inside. He wanted to help Sin out but he sort of made a promise to Thea that he wouldn't go looking for trouble anymore.

"Roy can help you." Thea offered while unaware of Roy's internal panic.

Surprised by the offer, Roy and Sin stared at Thea.

"I thought you wanted me to stay out of trouble," Roy was confused by the turnaround.

Thea shrugged, "I kind of like that you never turn away from someone who needs help." She grinned as she looked at him before she patted his shoulder, "I'll just get someone to cover the club."

Roy frowned, "What do you mean?"

"Oh, I'm coming with you." Thea clarified before she walked off to find one of her employees inside Verdant.

Roy groaned.

"So, we're doing this on our own?" Sin asked with a huff.

"For now," Roy ran a hand over his face, "And I can't exactly ask the Arrow for a favor without any proof to give him. I can't just tell him that a friend is missing without giving him anything to go off of." Roy knew that if he called upon the Arrow with nothing but a name and a suspicion to work on then the Arrow may walk away to deal with bigger problems.

"But you'll ask him?" Sin was feeling a little hopeful at the thought.

Roy nodded.

* * *

The rain had momentarily stopped and the sun had just set when Oliver and Diggle arrived at the warehouse. Oliver's time at the company was done for the day and after having a chat with his mother at lunch (about a company party the next evening to welcome her back), Oliver was free to do his other job without interference. And his first concern was finding the thief that robbed his company.

Unfortunately, Diggle was still focused on Oliver's latest plan for his CEO persona.

"Are you sure this is a good idea Oliver?" Diggle questioned the moment they exited the company car.

Oliver sighed, "I need to get my family back to normal." He didn't like the idea of a party but it was practically expected of the Queen family.

"I understand that but how is throwing a party going to accomplish that?" Diggle just didn't understand how a party would be appropriate. Sure he understood the lavish lifestyle the Queen family lived in but Moira Queen had just been released from prison after being partially responsible for the 503 deaths that occurred during the Undertaking. Who would go to a party to honor her?

"We Queens always throw parties and besides, this one is meant to welcome my mother back into the company." Oliver explained before he opened the door to the warehouse.

Diggle followed closely behind Oliver, "If you say so man." It was clear that Diggle still had his doubts but it was obvious that Oliver was staying firm on the party plan.

They continued their trek to the warehouse's main floor in silence. Everything looked to be in working order once again but Diggle's attention was immediately brought back into focus when Oliver suddenly stopped in front of him. If Diggle hadn't noticed when he did, he would have collided into his friend.

Diggle was about ready to question Oliver for his sudden stop when the billionaire motioned for his friend to be silent and look ahead.

The sight before Diggle was not something he was expecting to see. He quickly looked to Oliver and noticed the tense posture as he continued to stare ahead of him.

From his spot, Diggle could see a few computer terminals turned around and set up around the damaged centrifuge base. It was like a temporary workspace was established.

At one of the terminals was Agent Bolan who seemed to have taken off both his coat and suit jacket, leaving him with his white dress shirt that had the sleeves rolled up to his elbows. This didn't seem out of the norm for Diggle, it was the other agent that surprised him.

A few feet away from the terminal that Agent Bolan was working at stood Agent Anderson. He was leaning against another table that was perpendicular to Bolan's. Like Bolan, Anderson had discarded his coat and suit jacket while his sleeves were rolled up to his elbows. There were a pile of coats just behind Anderson's leaning form yet Diggle was surprised to find Felicity's dark purple coat on top of the pile of black fabric.

Now Agent Anderson's position wasn't what surprised Diggle, it was Felicity's position _beside_ the agent that brought on the emotion.

Like the agents, Felicity had shed her coat, leaving her red dress on display for all to see. Aside from her blonde hair, that dress was actually the most colored thing in the warehouse. Instead of working at the terminal with Agent Bolan, Felicity was tucked closely into Agent Anderson's side, so close in fact that he had one of his arms over her shoulder as both of his hands held a tablet just in front of their faces. If Diggle didn't know any better, he would have thought that both of them were involved in a Skype call or something like that.

But what Diggle found odd was the familiarity between Anderson and Felicity. Because of their close proximity, Diggle thought Felicity would be stiff or tense in her posture (like when strangers get too close to her before she could adjust to their presence) since she just met the agent earlier that day but that wasn't the case. He found no traces of discomfort; all he found was a sense of ease within her stance.

Before he could process what his observations could mean, Oliver was on the move.

"You found something?" Oliver asked a bit more harshly than usual as he approached the makeshift workstation. This caused Sam to turn around from the computer.

Felicity jerked in Dean's arms before she looked to Oliver with wide eyes, "We found something." She quickly turned her eyes away from Oliver and focused them onto her tablet as she rushed to bring a file to the screen.

Diggle noticed that Dean removed his arm around Felicity as he mumbled a few things into his tablet before he tapped the screen. The agent then straightened up and lowered his arm so that his tablet remained by his side before he looked to his partner.

Taking his partner's silent cue, Agent Bolan took charge. "Security footage here managed to capture the thief getting into a vehicle." He paused long enough to give Felicity time to pass her tablet to Oliver so that he could see the footage for himself.

No one missed how she immediately stepped back to Dean's side after passing over her tablet. It basically placed her between the agents.

Once the tablet was in the billionaire's hands, Sam continued, "Felicity was able to clean the footage up enough to pick up the plate number."

While Oliver watched the video, Diggle watched Oliver so he noticed that when the agent said Felicity's name so freely, it caused his friend to tense up even further.

Oliver nodded, "And?"

Dean rolled his eyes; he didn't appreciate the clipped and demanding attitude, "It belonged to a sugar refinery not far from here and it just so happened that they filed a report about their stolen truck a few days ago." He ended with a smug look directed at the billionaire.

Oliver narrowed his eyes a bit at Dean before he focused on Felicity and handed back her tablet, "Can you track the vehicle?"

Felicity sighed; the defeat was evident on her face, "We've been trying."

Before anything else could be said, a mechanical beep resonated throughout the group.

Oliver frowned, "What was that?"

As a unit, Felicity and the agents all looked between the computers and tablets until they came to realize that the beeping alert had originated from Felicity's tablet. With a few swipes on the screen, Felicity's eyes widened when she read the report that had set off her alert system.

"Felicity, what is it?" Dean asked once he noticed that she had a few false starts in regards to sharing the news.

"You're not going to believe this." Felicity looked up from her tablet, "The truck we've been looking for, it was just used to rob a blood bank."

Sam and Dean quickly looked to one another. They both had grim looks on their faces as they tried to figure out what this new development would mean for the case.

"Are you sure?" Oliver had a pensive look on his face when he asked.

Felicity nodded, "Yeah." She tapped a few things into her tablet before she pulled up the police report for the latest robbery, "Our guy just made off with 30,000 CCs of O-negative." Felicity looked worriedly between Sam and Dean.

Diggle sighed; he just couldn't believe these robberies, "What, he has super strength, likes blood? Please don't tell me we suddenly believe in vampires." He quipped but all he got were unimpressed looks, especially from the agents.

Dean stepped closer to Felicity to take a look at her tablet.

Oliver immediately noticed the move and he was surprised to see that Felicity immediately tilted the tablet towards Dean the moment she felt him in her personal space. She did it without him even asking, it was as if they've done the move many times before, so much so that it had become a routine for them. Oliver thought that the observation was odd considering that the agents just arrived to town that day.

"Vampire or not, who the hell needs that much blood and a centrifuge?" Dean cut in (bringing Oliver back to the conversation) as he skimmed the report that she pulled up, "Do they want to mass produce their own line of authentic Bloody Mary cocktails or what?"

Sam ignored his partner's last comment as he tried to work through the facts. "This guy seems to have an agenda. This robbery is more precise in the amount they took and which type it was. They specifically took O-negative and nothing else."

Everyone nodded along in agreement.

"That's the universal blood donor type, right?" Dean asked his partner and when he got a nod, he continued with his input,"Then I'm thinking either a massive transfusion or an O-neg. got very unlucky in an accident."

Felicity cringed,"Neither option sounds good."

"Either way we're missing something." Sam sighed as he pinched the bridge of his nose, "It's not adding up."

Sensing his partner's frustration, Dean took the lead and focused on Felicity. "Is there any way you could pull the security footage from the blood bank from here or do we need to go there to get it?" With his focus on her, he missed the stunned exchange between Oliver and Diggle; neither were aware that the agent knew of Felicity's computer skills since she was introduced as Oliver's EA.

Felicity thought about it for a moment. She knew that she could get the footage if she were in the Foundry but with only her tablet with her at the moment, there was a chance that she couldn't access the footage at that very moment. She was still surprised that her tablet had enough strength to get the blood bank alert that it got.

She started tapping a few things into the tablet, "I could try from here but there is a chance that I would need to go there." She looked up at Dean, "Think you can get me in?"

Dean smirked,"One step at a time."

Oliver blinked as he watched the exchange before him. Something didn't feel right to Oliver…and he was determined to find out.

"Let me know what you find." Oliver grunted out before he turned to walk out. With a public persona to maintain, Diggle quickly followed Oliver out.

Once they were outside, Oliver had a plan in mind.

"I want you to look into these agents." Oliver informed Diggle once their steps were aligned. "There's more to them than they're letting on."

"They seem fine to me." Diggle said as he gave his friend an amused look. While he had his own suspicions about the agents, he had a feeling that they weren't rooted in the same area as Oliver's suspicions.

Oliver stopped at their car and stared at the older man, "Just do it, please." He was not in the mood for any teasing whatsoever. There was just too much on his plate.

Diggle sighed, all joking put aside, "Oliver, when are you going to tell me what exactly we're up against?"

Instead of answering, Oliver got into the car.

.*.*.*.*.*.

"Well that went well." Dean commented after Oliver and Diggle walked out of his sight. He didn't like how the billionaire kept watching him; he had the urge to call him out on it but he knew he couldn't do that without exposing Felicity's connection to them to her _boss_.

Felicity sighed, her grip on her tablet tightened. She couldn't help but feel relieved over the fact that Oliver and Diggle were now gone, the guilt she felt for keeping relevant intel from them was tenfold when she was in their presence. It took a lot out of her to not blab about the intel because she knew that if she did that now then they may ask questions that she can't truly answer right now. For Felicity, it was better for her to keep busy and away from Team Arrow for the time being. Or at least until she figured out how she could share with them what she acquired from the Winchesters.

Felicity closed her eyes, "What now?"

The brothers looked to one another. They noticed her demeanor shift but they didn't press on it. They would wait for her to bring it up when she was ready to.

Instead, Dean started to unroll his sleeves, "We need to find that truck and the blood bank is our only lead." With that said and his sleeves smoothed out along his arms, Dean grabbed his suit jacket and put it on.

"I think I should do that back at the Foundry." Felicity explained with a deep exhale as she powered down her tablet for the moment,"I can be more specific with my searches there. Sadly my tablet can only do so much." She held up the device in question to make her point before she placed it into her bag.

Sam nodded,"Alright. But can you be away from work?" He was worried that her helping them would cause trouble for her at work, which he didn't want. She was the only one out of the three of them that had an actual paying job. The last thing he wanted was to cause Felicity any trouble with her work.

"Being friends with the boss has its benefits sometimes." Felicity dismissed quickly even though she had some worries; Isabel Rochev may be a problem but Oliver wouldn't mind since she was technically solving a crime made against the company.

"Okay then while you do that, we'll head to the blood bank and see if we could follow a trail from there." After suggesting that, Dean gave his brother his coat and suit jacket. Sam wasn't surprised to see that his brother was all ready to go with his own coat on.

"Could Digg be right though?" Felicity nibbled on her lower lip,"Could it be vampires?" She never faced a vampire before but she read the lore and it was nothing like the romanticized versions that Hollywood was spinning them into nowadays.

Sam sighed,"It's looking like it." He quickly unrolled his sleeves and put both of his jackets on,"It wouldn't be the first time that vampires robbed a blood bank before."

Standing by Felicity with her coat now in hand, Dean groaned at the reminder, "Don't remind me." He didn't want to remember that particular vampire case since it resulted in him becoming a vampire only to take a painful cure that thankfully turned him back into his human self.

Felicity gave Dean a sympathetic look as he helped her slip into her coat.

"Sorry." Sam grumbled, not only for bringing up that case but for the guilt he felt with it. Even though he was soulless during that case, with his memories back, Sam still felt guilty for the fact that his soulless-self had used his own brother as vampire bait.

"We better stock up on dead man's blood if vamps are our problem." Dean suggested as he made his way towards his brother, "It's been awhile since we've dealt with vamps."

"We'll deal with that tonight," Sam stated as he turned off the terminal they were using, "Let's just put everything back and then get Felicity back to her car."

Dean nodded and helped his brother rearrange the tables to where they were before with Felicity's guidance.

Once everything was put back into its place, they headed out with a game plan in mind.

Dean drove Felicity back to Queen Consolidated so that she could drive her car to the Foundry while the Winchesters headed to the blood bank to retrieve any more evidence about their thief.

* * *

***SPN*Arrow*SPN*Arrow*SPN***

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**Dialogue Disclaimer: **Any recognizable _Arrow_ dialogue came from 2x08 "The Scientist".

* * *

**A/N #1: **And there you have it! A little bit more supernatural theories were incorporated so I hope there was no confusion. Jealous!Oliver seems to have made an appearance too. So what did you guys think? What do you think will happen next? What parts of Arrow canon will remain and which ones won't? I'd love to hear your guesses!

**A/N #2:** Once again you guys are truly fantastic! Thank you so much for sticking with me on this! It truly means the world to me to have your support! **THANK YOU!**

**Latest Episode Thoughts: **What did you think of Arrow 3x15? My Olicity heart wasn't pleased yet my Oliver/Diggle brOTP was ecstatic. What did you think of SPN 10x14? While I love Dean vs. Cain, I am now worried for Dean. :( What did you think of either episode?

Both series return with new episodes [Arrow 3x16 &amp; SPN 10x15] on **Wednesday March 18th** (new day for SPN)!

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**Self-Promotion:** If you love the crossover idea, then check out my collection **"Mysterious Smoak"** for more oneshots set in the Supernatural/Arrow crossover universe!

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**Originally Published:** March 1, 2015


	4. DAY ONE – Colliding Confrontations

"**Supernatural Serum"**

**Disclaimer: **I don't own the characters; those belong to their original creators. The way it's all stringed together is of my making. No profit is being made out of this (*sigh* unfortunately).

Manipulations of the cover art/image are mine though.

* * *

**Backstory:**

\- Felicity meets the Winchesters in 2012 (reality; 2011-2012 / verse; 2012-2013 aka S7) = S9 (verse; 2015-2016)  
\- Timeline of "Arrow" has been pushed forward by **2 years** (therefore Oliver is shipwrecked in 2009 and saved in 2014) = S2 (2015-2016)

* * *

**TIME **= December 2015 (Winchesters have known Felicity for 3 years)

* * *

**Ages:**  
\- Dean Winchester (b. 1979 / 36)  
\- Sam Winchester (b. 1983 / 32)  
\- Oliver Queen (b. 1987 / 28)  
\- Felicity Smoak (b. 1990 / 25)  
\- John Diggle (b. 1979 / 36)

\- Roy Harper (b. 1993 / 22)

***Ages of the "_Arrow_" characters are the same here as they are on the show (it's just the changes in dates that are different)

* * *

**REASON why this is listed under "**_**Arrow**_**" only:** because of Felicity.

* * *

**Summary: **When Queen Consolidated is broken into by a man with suspicious strength, CEO Oliver Queen is surprised to find two federal agents on the case. Despite the new enemy in town, the Arrow is more confused by how these two agents seem to know Felicity Smoak. [Different spin on 2x08/2x09 with no Barry Allen] [Crossover with "Supernatural"]

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***SPN*Arrow*SPN*Arrow*SPN***

* * *

**Chapter 4:  
DAY ONE – Colliding Confrontations**

With their federal agent covers still intact, Sam and Dean were able to walk in and out of the blood bank crime scene without a problem. They were able to obtain the security footage of the robbery and ask their quick questions to the frightened employees before they left. There were in and out before any officer could question why two federal agents were involved in the case.

Once in the Impala, Dean got back on the phone with Felicity while Sam emailed the latest security footage to her. Felicity locked onto Dean's cell phone and tracked his GPS location throughout Starling City to further help Dean along in his drive.

The thief had about an hour head start on them but that lead didn't deter the trio.

As Dean drove, Sam and Felicity quickly worked on dissecting the security footage on their respective ends so that Felicity could input any data she needed into her traffic camera searches. They already had the truck they were looking for in the system so they just needed to find the traffic camera that spotted him in his quick escape and then work from there.

At first Felicity focused on the cameras surrounding the blood bank. From that camera, she determined which direction the thief went and then she followed the line of traffic cameras, hoping it stuck to a straight route along the major streets. Through math calculations to help determine the thief's speed, Sam was able to predict just how far ahead the thief had traveled from the blood bank. With that, it allowed Felicity to map out a search radius from the blood bank to work with. From then on, it was a collaborative effort to put together all the pieces as fast as possible while Dean tried to follow along on the road.

Once Felicity spotted the thief's truck on a live traffic camera feed, she relayed the location to the Winchesters before she called Oliver up, who was already hooded up and in the field with Diggle by this point.

From then on, Felicity was juggling between her calls with Oliver and with the Winchesters as they both went after the same target. Her concentration was scattered between traffic feeds of all three parties and their GPS pings on the city grid.

Oliver was the first to spot the truck.

* * *

"I have eyes on the target," Oliver reported to his team as he followed the truck on his motorcycle. On Oliver's command, Diggle was trailing behind him on another street so that the thief didn't spot his car driving down the empty street.

Quick clicking on the keyboard could be heard over the connection, "_I've got your location. Be careful. We really don't know what this guy is capable of._" Felicity responded quickly before she continued clicking on the keyboard for a few moments before it stopped. Oliver knew instantly that Felicity had muted her comm. link. When she muted the link from her end, it didn't stop her from hearing them in the field. It just stopped them from hearing the incessant typing that occurred when she had nothing to say. The same would happen if either Oliver or Diggle muted their link; they could hear her but she couldn't hear them. They rarely muted their communications though.

"Understood. I'm going in." Oliver announced before he revved his engine and approached the stolen truck.

The hooded vigilante swerved around as he tried to get ahead of the truck. When the thief started driving to block him off, Oliver had to think of something else while staying in the thief's blind spot.

Because of the truck's structure, Oliver knew that the thief could only see him through the side mirrors. It gave him a bit of an advantage to work with. When he found the opening he needed, Oliver took out his bow and shattered the right side mirror on the truck with one of his arrows. With the right side taken care of, Oliver righted himself on his motorcycle before he shot one of his grappling hook arrows onto the top of the truck. Once Oliver was sure that the arrow penetrated the metal framing and stuck, he used it to pull himself up the back of the truck and onto the roof of it. He kept his body close to the surface as he crawled his way to the front of the truck. Along the way, Oliver took out one of his tracking devices, turned it on then attached it to the roof's surface. Even if the frequency was noticed, no one would be able to spot the device unless they inspected the roof themselves. Oliver's attention quickly turned back to the road when he heard his motorcycle skid and crash into the side wall.

Taking that as a sign to attack, Oliver jumped to the hub of the truck before he grabbed the edge and swung himself over so that his feet kicked the driver inside. He knew that he wouldn't have been able to do the move if the driver's side had kept its door in place. Without the door, it gave Oliver the perfect place to attack.

When Oliver kicked the driver he was instantly met with a hit to his abdomen, causing Oliver to lose his hold and dangle along the side of the vehicle. Thinking quickly, Oliver planted his feet onto the driver side's step before he pulled himself up to his full height. Oliver threw three hard punches to the driver's masked face before the force of the punches pushed the driver to look the other way.

Oliver thought he had done it, that this was the moment where he'd wrestle the steering wheel until he controlled the vehicle to a safe stop but that wasn't the case. Oliver was stunned to find that his punches hadn't knocked the thief out. Instead the thief slowly righted himself and turned to stare at his opponent before he delivered a hard punch into Oliver's face. The force of the hit threw Oliver back but because he held onto the door's frame tightly, he swung around and landed on the hood of the engine.

Oliver groaned at the impact. He hadn't felt a hit that hard in a very long time but before he could recover from the hit, a loud shattering sound was heard behind him before he was harshly pulled back into the cab and right into the passenger's seat. Pieces of glass flew everywhere and Oliver used that distraction to pull an arrow from his quiver before he stabbed the arrow into the thief's leg.

Furious by the move, the thief punched the vigilante again. The force of the punch was so hard that Oliver didn't just get thrown back into the passenger's side door, the force pushed not only Oliver out of the truck's cab but it broke the door right off its hinges. Oliver hit the ground with the metal door underneath him. The momentum from the punch forced Oliver to skid down the road, the loud metal screeching against the concrete below him, until he crashed into a pile of trash.

Oliver groaned as he tried to pull himself out of the trash pile. By the time he resurfaced, the truck turned onto another street. Oliver cursed up a storm as he tried to straighten himself up, however when he noticed that he was still holding something, he looked down and saw that the arrow he had stabbed into the thief's leg was still in his hands. However, the surprising discovery wasn't the arrow in his hands… it was the condition it was in. The carbon arrowhead was not only bloody but damaged…it was as if it tried to penetrate the target and yet failed on impact. That had never happened to his arrows before.

Oliver frowned at the damaged arrow.

"_Oliver?_" Felicity's voice interrupted him from his inspection, "_I still have sight of the truck but I have no visual of you. Are you okay?_"

"I'm fine," Oliver grunted as he slowly got to his feet. "Is the tracker transmitting?"

Oliver heard a few keyboard clicks over the comm. link as he made his way towards his motorcycle. He did a quick check and he was relieved to find that there was no severe damage to his bike. He could still ride it back to the Foundry if he wanted to.

"_I've still got a signal_," Felicity reported before a few more clicks were heard around her, "_I still see him in the traffic cameras too._"

Oliver was relieved to hear that. After that fight with the thief, there was no doubt in Oliver's mind just who he was dealing with, or in this case what he was dealing with. Before then he only had speculations but now he had his facts. He hasn't fought anyone like the thief since his time on Lian Yu.

"Keep your eyes on him, I'm heading back." Oliver commanded as he mounted his motorcycle, "Dig, I'll meet you back there." He packaged and secured the damaged arrow before he revved his engine.

"_Roger that_," Diggle reported from his end of the comm. link before he changed directions and headed back to base.

After doing a quick check of the area to make sure that he didn't leave anything incriminating behind, Oliver headed back to the Foundry.

.*.*.*.*.*.

After hearing confirmations from Oliver and Diggle about returning to the Foundry, Felicity muted her comm. link to them before she focused back on the Bluetooth device on her other ear. "Oliver is heading back, are you continuing forward?"

"_We've got nothing better to do_," Dean replied from the other end of the call, "_Just tell me where to go Fee_."

Without hesitation, Felicity gave the Winchesters the tracker's GPS location and the general direction the truck was heading in.

When Felicity first told Oliver about spotting the truck, she made sure to remind him about the tracking devices that he carried with him. She wanted him to use one on the truck just in case they lost him again. She even rambled off her explanation soon after realizing that the suggestion could have been interpreted as being an offensive one. It wasn't that she didn't have faith in Oliver's abilities to stop the thief…she just didn't want to take any chances especially if the thief was really a supernatural entity in disguise. Thankfully Oliver was too focused on fighting the thief to take her suggestion as an offensive one.

Once she told Oliver that news, she warned the Winchesters about it. She didn't want them bumping into one another during this chase. Dean understood the warning and trailed behind, giving Oliver the reigns. Once the tracker's signal went online on Felicity's network, she informed the Winchesters and passed along the tracker's frequency tag to Sam so that he could track it on his laptop.

Throughout Oliver's fight with their thief, Felicity watched the four GPS pings rushing down the highway at three separate positions while trying to find any traffic cameras to help her see them along the way. With the truck riding along the lower highway roads, there were fewer cameras set up there so Felicity only had the GPS to rely on for most of it. During this time, Felicity's communication link with her Team Arrow partners had been muted while she stayed on the line with the Winchesters. She only unmuted the link when responding to Diggle whenever he asked for an update. She had to constantly mute and unmute the two connections just to keep the confusion and her secret at bay.

Now with Oliver heading back to the Foundry, the Winchesters could follow the GPS tracker on the truck. It was Felicity's 'Plan B'.

"You're closing in on him. You should have a visual of him shortly." Felicity commented as she watched the Impala's GPS slowly gaining on the truck's GPS tracker.

"_We've got a visual but we can't keep it for long without him noticing._" Dean confirmed just as he turned onto the street the truck was driving down. There weren't many vehicles on this particular road and it looked like many buildings were closed down for the evening. If he stayed on the thief's trail for too long, it would expose their motive to him which they couldn't have.

"_Felicity, how long is this tracker good for?_" Sam questioned as he checked a few things on his laptop; he was still receiving a strong signal from the tracker but he worried that they wouldn't have it for much longer. "_We may have to follow him through the signal instead. We're too out in the open like this._"

With the GPS signals showing up on an electronic grid of the city, Felicity pulled up a different map that showed the city's industrial plans. Once she matched them up, it was easy for her to figure out where the thief was headed, for now at least. "It looks like he's making his way toward the Glades. There are practically no working traffic cameras in that area, especially after the Undertaking. I would lose my visual of him."

Sam and Dean looked to one another before Dean focused on the road while Sam focused on the cell phone.

"_Would the tracker still work though?_" Sam asked again.

"The tracker shouldn't be affected by it." Felicity was sure of this, "It's meant to last the night at least. I'm still working on the upgrades for them." For a while she's been working to perfect the technology that went into Oliver's tracking devices. They were meant to be untraceable and undetectable with a powerful signal. It's taken her some time to work on each aspect of the device but she hoped to transfer it to Oliver's arrows. It was a work-in-progress project but she was glad she was making progress on it.

"_As long as the signal holds, we can work with that_," Dean added as he kept his distance from the truck. Once Dean saw the thief make a turn, he decided to change things up. Instead of turning to follow, Dean continued forward another block before turning. The move allowed for Dean to drive along a parallel street to the thief's route, it was something Sam confirmed after pulling up their own GPS onto the map. The Winchesters were determined to follow this thief until the signal died on them.

"Just be careful, try not to engage if you don't have to." Felicity advised the brothers before she noticed movement in the cameras placed outside Verdant's back alleyway. It took a few minutes before Oliver made himself visible in the camera. "Oliver's back, I've got to go." She rushed out as she erased the GPS signal she had of the Winchesters from her screen. "I'll call you guys back later."

She didn't wait for the brothers to respond before she ended the call and removed her Bluetooth piece from her ear.

She swiveled around in her chair just as the Foundry's door opened up. Her eyes widened when she saw Oliver slowly descend as he favored his left side.

_What the hell happened? _Felicity thought as she rushed to his side.

At first, Oliver refused any help. Not being deterred by this, Felicity focused on putting away his bow, quiver and other gadgets before she helped him out of his hooded vest. He only allowed her to help when it became clear to him that moving his arm a specific way jostled his side too much to his liking. Even stretching out his left side disturbed the injury he already received there.

When Diggle finally joined them, Felicity was starting to bandage Oliver's side up after she had applied some of the healing paste that Oliver kept stashed in the med kit; it was one of his creations from the island.

"Yeooww!" Oliver suddenly yelped in pain when Felicity pressed a little too hard into his side. It was the first distinguishable sound he made since Diggle joined them.

Felicity winced; she didn't mean to add to his pain. "Sorry," She mumbled as she pushed the last part of his bandage into place. She caressed her fingers around the wound before she told him that she was done.

Oliver whispered his thanks to Felicity as he put his sweater on properly.

"You were right to ask if I knew more than I was letting on," Oliver started as he zipped up his sweater and righted himself in his seat before he faced a patient Diggle, "I've seen men with abilities like that before."

"You have?" Felicity sputtered with wide eyes, "Where?" Her mind started running through all possible entities he could have encountered. Did he face off against vampires or werewolves? Was it a demon or a wraith? There were just so many possibilities that Felicity started to freak out a little inside.

Oliver looked to Felicity with a frown, "The island." He watched as her jaw dropped just a bit before she reeled her reaction in. The response confused him.

Where else would he have come across something like this man? As a playboy billionaire before the island, it would have been plastered all over the news if he had encountered a man with these abilities.

"My second year marooned there, we-" Oliver's paused at his slip-up, something both Felicity and Diggle noticed yet said nothing about it, "- I came across the remains of a Japanese World War II military project. It was a serum designed to create human weapons."

"Human weapons," Diggle scoffed at the thought, "My God, what's next? Aliens?"

"Diggle, this is real." Oliver cut in sharply, "Those five years that I was away, I came across _things_ that just defy explanation." Oliver shook his head at the thought, "There's a doctor, his name's Ivo, and he came to the island to test the serum on people." Out of the corner of his eye, Oliver could see Felicity tense up at the mention of human testing; he couldn't blame her for that reaction. "The ones that survived…their endurance, reflexes and strength were all enhanced."

"And you think this Ivo's in Starling City?" Diggle questioned, picking up on the connection as soon as it was presented to him.

Oliver shook his head, "He's dead." He gave a pointed look to Diggle, "And so is everyone that he injected with the serum, the last of which I burned." It was because of this fact that Oliver had no clue as to how the serum appeared in Starling City. Ivo was searching for the serum so that he could study it and validate that the serum did what it was rumored to do. When it came to the serum, all Ivo had were theories, so there was no way he could manufacture it without the actual serum. Once Oliver had destroyed it, he eliminated any chance of it being studied or replicated.

Diggle frowned at the thought, "You think someone found the recipe."

Oliver nodded; he didn't know how it was possible but it seemed like the only viable option for the serum's return.

"And this formula wouldn't happen to need…" Felicity gulped as she trailed off.

Oliver nodded, stopping her from completing her sentence, "The centrifuge and a large supply of blood are needed. I think someone wants to make more of it," Oliver sighed, "A lot more."

Diggle took a seat with that news.

Felicity closed her eyes and sighed, "Why couldn't you have been marooned on Aruba?" She reopened her eyes again at the thought. She couldn't help but wonder it since Oliver seemed to have come across a lot of things no one was meant to on a _deserted_ island.

"There's a third component…a strong sedative." Oliver slowly twisted in his seat to grab the damaged arrow that he had stabbed into the thief's leg earlier from his discarded vest. He left it in its plastic baggie for Felicity as he handed it to her.

Felicity gulped as she accepted the bloody arrow. "I think I preferred it when you left these in people." She commented as she tried to have as little contact with the arrow as possible, despite being in a baggie. Based off the damaged arrowhead, Felicity would have thought that Oliver rammed it into a concrete wall if it weren't for the blood covering it.

"I need you to analyze the blood on the arrowhead." Oliver explained after relinquishing his hold on the arrow,"If we can figure out which sedative they're using…"

"…We can figure out where the next robbery will be." Diggle continued, having caught on to Oliver's plan the moment he saw the bloody arrow.

Felicity nodded, "I will get right on it. I'll update the agents along the way too," She turned to grab her things before she walked out of the Foundry.

When the door closed with a bang, Diggle turned back to look at a scowling Oliver. The older man chuckled as he grabbed a face wipe for the vigilante.

"I think our Miss Smoak is smitten." Diggle teased as he passed the face wipe to Oliver, who stiffened at the mention yet he took the wipe to wash the grease paint off around his eyes. Diggle couldn't help but feel amused by Oliver's demeanor.

"Diggle, what did you find out about them?" Oliver deflected as he cleaned the grease paint off.

Diggle's previous amusement vanished. "You're not going to like it."

* * *

**Meanwhile:**

Darkness covered the property which is all that the Winchesters needed as it helped to hide their position. Dean sat behind the wheel with his camera in hand, taking photos of their target every few minutes while Sam sat beside him with his laptop, scanning through security footage from the surrounding cameras.

After disconnecting with Felicity, the brothers had followed the thief from afar. The tracking device's signal had shown the thief driving through the Glades before he left the chaotic area and made his way towards the outskirts of town. It didn't take long for the brothers to realize that the thief was making his way towards the industrial district.

Initially they thought that the fenced-in district would be a roadblock for them but the thief took care of that for them by ramming his stolen truck into the gates and driving through. However before they entered, Sam hacked into the district's security camera feeds and through those he watched where the thief's final destination was before Dean followed. With a quick search through the district's directory, Sam was able to find that the empty warehouse the thief had stopped at belonged to the same sugar refinery that he stole the truck from.

With help from the security feeds, Sam directed Dean through the district to a place that was close enough for them to park and spy without being noticed. Once parked, Dean grabbed his surveillance equipment (which mainly consisted of his camera and its accessories) without disturbing the leftover ashes of saffron, skunk's cabbage and trillium they created earlier to hide their scents from vampires. Dean quickly started snapping photos as he watched the thief unload the stolen blood bags into the warehouse. He even took some photos of a parked car near the warehouse entrance but he couldn't get a clear shot of the license plate and he had no glimpse of the owner just yet. He was biding his time for that photo. He was also waiting for when the thief would remove his mask.

While Dean took pictures, Sam's focus remained on the security feeds while trying to see who else had earlier access to the area. Unfortunately for Sam, he saw the parked car appear in many camera feeds but either the angle wasn't right for a view at the license plate or the camera was stationed on the opposite side of the driver. It was getting frustrating but he knew he couldn't give up. He saved all footage to his laptop in hopes of showing it to Felicity later on.

"How long do you think we'd have to stay camped out here?" Dean asked without taking his attention away from his camera.

Sam sighed, "This is our only lead Dean. We have to stick with it."

Dean groaned, "I was hoping you'd say something else." As much as he loved his baby, he didn't want to camp out in the Impala again.

"Well Felicity is counting on us to finish what Oliver couldn't do," Sam reasoned as he searched more into the security system. "And I get the impression that this isn't Oliver's usual when it comes to bad guys."

Dean scoffed; he still couldn't believe how much 'training' Oliver had while he's been missing for the last five years. Felicity said that Oliver had exceptional skills because of his time on the island but Dean wasn't buying it. Five years didn't compare to the thirty plus years of training that he and Sam had to endure.

Before Dean could refute Sam about Oliver's vigilante antics, a low sound resonated throughout the Impala. It took the brothers a few seconds to realize that it was one of their phones that were ringing.

It took another few seconds for Dean to pull out his cell and answer the noisy device.

"Yeah?" He answered without checking who it was.

"_Where are you guys__?_" Felicity greeted instantly.

"Oh, hey Fee. Hold on," Dean pulled his phone away and switched it to speakerphone before he placed it on the top of the Impala's dashboard, "You're on speaker. What's up? Where are you?"

"_In my car. Where are you guys?_" She asked again, her voice echoed within the Impala.

"We're still following the tracker. It stopped within the industrial district. There are a bunch of warehouses here but the tracker shows that it stopped at a warehouse that's registered under the same sugar refinery that the truck was stolen from." Dean explained while his attention was still on his camera and his focused area.

"From the looks of it, it hasn't been used in a while." Sam continued as he pulled up the information for the warehouse, "It probably hasn't seen any action since the thief started to set up shop there. We're just doing recon right now."

"_A lot of warehouses in that district had shut down shortly after the Undertaking._" Felicity commented, "_I'm not surprised that he's camped out there._"

"Exactly. So what's happening on your end?" Dean asked, "How's your emerald archer doing?"

Felicity huffed at the insinuation yet didn't bother to correct the hunter, "_He's pretty bruised up but he did divulge some information to us. Now normally I wouldn't share what he did when it was said in confidence but it's relevant to the case so I figured that for this situation, I'll make an exception._" Felicity rambled, completely unaware of the amused looks the brothers shared with one another as they listened. When she said nothing more, the brothers' amusement increased.

Dean cleared his throat, hiding his building laughter in the process, "What's the information Fee?"

"_Oh, right!_"

The brothers couldn't help but snicker at the clear astonishment, as if she couldn't believe that she forgot to reveal the information she was just raving about to them, in her voice.

Felicity inhaled deeply before she started, "_Apparently the super-strength is the outcome of some serum that was meant to create the perfect super-solider_."

"A serum?" Dean interrupted,"So we're not dealing with vampires?"

"_Apparently not. Oliver came across the serum during his time on the island. The serum was supposed to be some Japanese military project back in World War II,_" Felicity quickly explained. While the theory fascinated her, the reality only scared her.

Dean gave an incredulous look to his brother at the news. _What the hell, _Dean mouthed to Sam, who just responded with an unknown shrug.

"I thought he was on a _deserted_ island for five years." Dean questioned as he rethought everything he knew about Oliver's time lost at sea.

Felicity sighed, "_Yeah…I'm slowly learning that that is not the case at all._" She couldn't blame Dean for his suspicions. There were still a lot of things that Felicity didn't know about Oliver's time away on the island.

Before Dean could question the reliability of Oliver's claims, Sam interrupted with his own discovery.

"Hold up, I think I read about that…" Sam's brow furrowed as he tried to remember what he had read (as if it were on the tip of his tongue), "I believe it was _Project Mirakuru_."

Dean gawked at his brother, "Where the hell did you read that from?"

Sam frowned, "When I was looking through the Men of Letters' archives the other day. I was helping Kevin with his translations." He explained, much to his brother's disbelief. "If I remember correctly, the file said that the serum altered human subjects by giving them enhanced strength, endurance, reflexes and health. The only reason they had the file was because the surviving subjects mimicked a few supernatural entities. Those that died had bled out through their eyes, which is already an unusual way to go."

Out of the corner of his eye, Sam saw Dean flinch. Sam couldn't really blame Dean for the reaction since it too reminded him of the Bloody Mary case they handled back in 2005. When they were moments away from banishing the spirit, Bloody Mary had caused them to bleed from their eyes like her previous victims had done so before they died. The sensation was always unwelcomed.

"Why the hell didn't that come to your mind yesterday?" Dean asked through gritted teeth. He couldn't help the anger because knowing about the file beforehand could have saved loads of time and trouble for them.

Sam's eyes narrowed at Dean, "The file said that the project was lost during the war. How was I supposed to know that it would resurface in Starling City of all places?" His voice started to get louder,"If anything, it would have popped up in Japan first before it traveled all around the world to wreak havoc here." It may have been the late hour and the close quarters but Sam couldn't help but react to his brother's anger. Sam didn't appreciate the attitude directed at him. It wasn't like he purposefully kept the file from Dean; the file just never came to mind as a possibility, given its origins.

Sensing an argument brewing between the brothers, Felicity spoke up, "_Oliver said that it looked like someone was trying to reproduce the serum even though he destroyed the original serum when he was on the island._" She took a moment to take a breath,"_The centrifuge and the blood supply were key components in creating it._"

"Were there any other components to this unwanted recipe?" Dean asked while still glaring at Sam.

"_A strong sedative is the last part. It's actually one of the reasons why I called. During the fight, Oliver managed to stab the thief with one of his arrows and he brought it back all bloody and whatnot._" Felicity explained as she glanced at her bag, where the bagged arrow was currently hidden.

The news brought Dean's attention back to the phone, "He brought back a bloody arrow?"

"You could analyze the blood for the sedative that was used." Sam interrupted before Felicity went on a tangent about Oliver's Arrow ways, "It would give your team a sense of where this guy will strike next."

Felicity hummed. "_I'm heading off to see a friend of mine in forensics about that now. I'm hoping she can let me use her equipment to do the tests._" Normally Felicity could perform the tests herself but without access to the more sensitive equipment that she needed, she had to look elsewhere for help. "_Did you find anything from the recon?_"

"It's starting to feel more like a stakeout," Dean revealed with a sigh, "How about we meet up at your place tomorrow morning and we'll swap intel? Will the blood results be done by then?"

Felicity mulled the answer over for a second, "_They should be. If I can, I'll try to find out more._"

"Don't exhaust yourself too much, Felicity. Get some rest." Sam suggested softly.

Felicity sighed, "_I'll try. Good luck._" The brothers both said their quick goodbyes to her before they ended the call.

Dean picked up his cell and pocketed it again with a sigh, "We need to know more about this serum."

Sam nodded as he dug out his phone, "Should I call Kevin now?"

Dean looked down at his watch, "With any luck, he'll still be up working on that tablet. He deserves a break."

"A break from researching is usually _not_ more research," Sam countered with a scoff as he dialed the Bunker.

Dean rolled his eyes, "Whatever." He shifted his attention back to the warehouse and sighed, "And we really should have brought some take-out with us."

* * *

***SPN*Arrow*SPN*Arrow*SPN***

* * *

**A/N #1: **And there you have it! I'm so sorry for the long wait but what did you guys think? What do you think the brothers will find on their recon? What do you think Diggle found out about these 'agents'?** Let me know about your thoughts and predictions in a review! **I'd love to hear them! :D

**A/N #2:** I can't say it enough but you guys are truly fantastic! Thank you so much for your support on this story! It truly means the world to me to have your support! **THANK YOU!**

**Latest Season Thoughts: **So what did you think of Arrow Season 3 and Supernatural Season 10? Are you excited for their Wednesday returns in October?

Both series return with new episodes [Arrow 4x01 &amp; SPN 11x01] on **Wednesday October 7th!**

* * *

**My After Show Saga Project: **So part of the reason why I stopped updating was because I was starting up my own after show series. Basically they are just videos of me talking about the latest episodes and I wanted to see whether or not I should do them when the new season begins in the Fall. While I haven't posted anything this month because I've been sick with a terrible cough, I hope to update the series with the latest Comic Con news.

So I hope you guys could pop by and check it out at Youtube with the  
URL: **channel / UCJJ-mSaVeXiFxl1pinfU4Iw/videos#_=_** after the usual . com.  
Otherwise look up **"After Show Saga"** or **"Mel D-SPN-A"**.

* * *

**Originally Published:** July 30, 2015


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